1. Field of the Invention
The present field of the invention is related to a wafer container, and more particularly, to a wafer container disposed with purgeable supporting component for gas to form a gas flow in the wafer container.
2. Description of the Prior Art
The semiconductor wafers are transferred to different stations to apply the various processes in the required equipments. A sealed container is provided for automatic transfer to prevent the pollution from occurring during transferring process. FIG. 1 shows the views of wafer container of the conventional prior art. The wafer container is a front opening unified pod (FOUP) which includes a container body 10 and a door 20. The container body 10 is formed with a pair of side walls 10L and a top surface 10T and a bottom surface 10B adjacent to the pair of side walls 10L. An opening 12 is formed on one sidewall and a back wall (not shown in Figure) is formed on the other sidewall opposite to the opening 12. Wherein a plurality of slots 11 are disposed respectively on the pair of sidewalls 10L for horizontally supporting a plurality of wafers. The door 20 includes an outer surface 21 and an inner surface 22, and joins with the opening 12 of the container body 10 with the inner surface 22 for protecting the plurality of wafers within the container body 10. In addition, at least a latch hole 23 is disposed on the outer surface 21 of the door 20 for opening or closing the wafer container. According to the aforementioned, due to that the wafers are horizontally placed within the container body 10, thus, a wafer restraint component is needed in the FOUP to prevent the wafers from displacement or from movement toward the opening 12 of container body 10 occurring during the wafer transportation due to vibration.
FIG. 2 is a view of a front opening unified pod (FOUP) as described in U.S. Pat. No. 6,736,268. As shown in FIG. 2, the inner surface 22 of the door 20 is disposed with a recess 24 and the recess 24 is extended from the top 221 of the inner surface 22 to the bottom 222, and is located between two locking components 230 (inside of the door 20). A wafer restraint module (not shown in to Figure) is further disposed in the recess 24. The wafer restraint module consists two wafer restraint components 100, and each wafer restraint component 100 includes a plurality of wafer contact heads 110 to sustain corresponding wafers, so as to prevent the wafer from displacement or movement toward the door opening due to vibration occurring in the wafer transportation procedure.
The slots 11 on two sidewalls 10L of the container body 10 and the wafer restraint module on the inner surface 22 of the door 20 are used respectively for supporting and restricting the plurality of wafers within the container body 10. Friction between these supporting components and restraint components and the wafers easily occurs during the transferring process of wafer container and results in generation of particles. When particles are generated inside the container body 10 of wafer container, these particles may stay on the surface of wafers or pollute the wafers, which cause decrease of yield for later production of chips. Therefore, a material with wear-resisting property can be used for the design of supporting components and restraint components of wafer container to prevent from too many particles generated when supporting components and restraint components contact the wafers. As shown in FIG. 3, which is a sectional view of supporting module on two sidewalls of wafer container as disclosed in U.S. patent No. 2006/0283774. This supporting module is formed by a plurality of supporting components 500 vertically arranged at intervals, and the surface of supporting components 500 is coated with a layer of resin 501 of low friction for preventing particles from being generated due to friction between supporting components 500 and the wafers. However, since the layer of resin 501 according to the design is with a slope, the wafers can only be supported near the edges when being supported by the layer of resin 501. Thus when the size of wafers is larger, the wafers droop or sink more easily, which not only makes it easier for wafers to crack but also results in chips or damage to wafers more easily when the mechanical arm exports the wafers.
In addition, in some other designs, a blowout opening or an edge is provided inside the wafer container, for example, close to where the wafers and the above-mentioned supporting components or restraint module contact, for carrying particles generated due to friction away from the wafers. As shown in FIG. 4, which is a view of purgeable supporting module that can be disposed inside the wafer container as disclosed in U.S. Pat. No. 6,899,145. This purgeable supporting module includes a hollow main body 600 which is fixed to sidewall of container body of wafer container with a plurality of vertical supporting components 601 extending to the interior of container body for supporting the plurality of wafers inside the container body with upper surface 602 of supporting components. And the side surface 603 of the supporting components is a bar-shaped slit for gas of the interior of hollow main body 600 to be blown out from for preventing particles generated due to friction from forming on the surface of wafers. In the above-mentioned structure, since the bar-shaped slit is disposed on side surface 603 of supporting components 601, the supporting force may to not be enough and displacement or overlapping of wafers may thus occur and cause more serious damages to wafers. Moreover, when wafers are carried by the upper surface 602 of supporting components 601, the contact area between wafers and supporting components 601 is fairly large, which makes it much easier for particles to generate. And since the length of the bar-shaped slit is about as long as wafers, the gas flow may be small or larger purge equipment may be needed for providing larger gas flow to form effective gas flow. Therefore, a purgeable supporting module with a more comprehensive design is needed for being disposed in the wafer container to effectively prevent particles from generating and forming on the surface of wafers.